<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title></title>
</head>
<body>
<div></div>
<script>
//     var div = document.getElementsByTagName("div")[0];
// 
//     div.style.cssText = "width:100px;height:100px;background-color: pink";
// 
// //    div.style["border-radius"] = "50px";
//     div.style["zIndex"] = "1";
// 
//     //很多浏览器支持的是
//     div.style.borderTopLeftRadius =  "50px";
//     div.style.borderBottomRightRadius =  "50px";


	var div = document.getElementsByTagName("div")[0];
	div.style.cssText = "width:100px;height:100px;background-color:pink";
	// div.style["border-radius"] = "50px";
	div.style["zIndex"] = "1";
	
	div.style.borderTopLeftRadius = "50px";
	div.style.borderBottomRightRadius = "50px";
</script>
</body>
</html>